1. Field of the Invention
The present invention relates to a digital color copying machine capable of composing an image and controlling the color of the composed image with ease.
2. Description of the Prior Art
A digital color copying machine has been known in public in the prior art, in which an image data signal of an original document taken by image taking elements is converted into a digital form image data signal and is printed to be formed on a sheet by an electronic photographic method in correspondence to the image data signal of digital form.
In a digital color copying machine, a color reproduction ability is the most important point of the performance, i.e., it is most important to make the color of a copied image as similar as possible to that of the image of the original document. Even in case there appears little difference between the color of the copied image and the color of the original document in one time copying operation, when a recopying operation, so called a generation copying operation, is performed by copying the image formed by the previous copying operation as the original document, there occurs a large difference between the color of the recopied image and the color of the original document.
In a conventional digital color copying machine, there is provided a color control device for adjusting the color of an image to be formed by a copying operation and it is possible that an operator of the copying machine operates said color control device so as to vary and adjust the color of the image to a color as similar as possible to that of the original document or to a color the operator likes.
In the conventional digital color copying machine, however, it can not be seen what color adjustment has been done without seeing the image formed by every actual copying operation of the color control device. Therefore, many times of copying and printing tests must be done for adjusting the color, so that a lot of sheets and expensive color toner are wasted and that a lot of time and labor are needed, resulting in a high price of the running cost.
Moreover, in the conventional digital color copying machine, there is provided an image memory unit for once storing an image in order to compose an image and when a character is copied to be printed or an image is formed in a work station, the image is stored in the image memory unit as a data with two values without gradation and since the image is composed on the basis of the two-value data without gradation stored in the image memory, it is impossible to correct the color of the image data read out of the image memory unit so that it is difficult to correct the color of the image when the image is composed.
Moreover, there is another problem that, since it is impossible to set different copying magnification/minification rates to the respective images to be composed, the image editing work is troublesome.